Brushes is easy but it costs money. You could look into either Superior Drummer, BFD or EZDrummer. All three have brush samples, midi based and come with midi loop libraries. Prices range from $150-$190 for EZDrummer with Jazz EZX add on or up to $400 for BFD or Superior Drummer. The other option is audio loops which you could get from Beta Monkey Music.

As far as guitar slide, I don't think there is anything convincing out there.